1. Field of the Invention
The present invention generally relates to an ultra-small and light-weight image pickup apparatus such as a so-called micro MV video camera and a digital still camera, and particularly to an image pickup apparatus including a miniaturized shutter mechanism serving as a lens cover to protect an image pickup lens and a clutch mechanism for avoiding a shutter mechanism from being broken and in which a highly-precise shutter mechanism can be obtained by simple and easy assembly.
2. Description of the Related Art
As digital video cameras including an external liquid-crystal display monitor panel openable and closable to the video camera body through a hinge mechanism and digital video cameras with a memory card such as an IC (integrated circuit) recording media that can record or reproduce a recorded image as a moving picture or a still picture become progressively small in size and light in weight recently, video cameras which are more miniaturized and light-weighted, that is, so-called palm-held size digital video cameras are now under development.
On the other hand, in the above-mentioned ultra-small digital video camera, it is requested that its shutter mechanism to protect an image pickup lens should be smaller in space and that such shutter mechanism should be simple in arrangement and high in assembly accuracy. In addition, it is requested that the above ultra-small digital video camera should have a safety mechanism for avoiding a shutter mechanism from being broken when external force is applied to a shutter plate unintentionally or preventing a motor from being applied with an overload during the shutter plate is being opened or closed by a motor drive mechanism.
The cited patent reference 1 has disclosed a small and light-weight lens cover apparatus for opening and closing a lens cover reliably and which can prevent a lens cover drive mechanism from being damaged even when external force is applied to the lens cover.
[Cited Patent Reference 1]
Official gazette of Japanese laid-open patent application No. 2000-261699
The above-mentioned lens cover apparatus comprises a cam portion integrally formed with a rotary dial type operation mode selecting switch for selecting camera operation modes and which has cams with different radiuses required in the shooting mode and the non-shooting mode, a substantially V-like protruded portion slidably in contact with a cam portion with its one member, a lens cover drive arm for engaging one end of the lens cover with the tip end of the other member of the V-like protruded portion, a spring for spring-biasing one member and the other member in the direction in which they become distant from each other and a drive lever composed of a stopper member for restricting the detachment between one member and the other member under spring force of this spring and a resilient member for spring-biasing the protruded portion of one member so that the protruded portion may constantly and slidably contact with the cam portion under spring force to open and close a lens attachment opening by the lens cover moved when the drive lever is moved in unison with the cam portion. The lens cover apparatus having the above-mentioned arrangement is extremely complex in arrangement, and therefore it is not suitable for use with the ultra-small digital video camera. Also, although such lens cover apparatus can easily be assembled into an image pickup apparatus such as a so-called camera which is long in the horizontal direction and which has a wide front surface to mount an image pickup lens, it is not suitable for use with a so-called video camera having a wide side surface portion to mount a holding portion and which has a narrow oblong surface in the longitudinal direction to mount an image pickup lens.